Both of those are quite old, before 8.3 was branched from 8-stable. I would expect that code to be in already. However the first link is a kernel panic in 9beta running on Atheros CPU (MIPS?), not relevant here I think. The second link references -head which is also 9. Where are you seeing this listed as supported by 8?

Shows all Atheros supported except for a specific one which is not AR9220.

What is the deep down dirty way that I can check in SSH to see if it's really supported or not?Results of: pciconf -lath0@pci0:0:12:0: class=0x028000 card=0x2096168c chip=0x0029168c rev=0x01 hdr=0x00

Using the latest developmental image, in Access mode (b/g), I can see "up" but "n" shows "no carrier". Despite showing up in b and g mode, I can't see the SSID though when I search for it. Could it be due to my 5Mhz antennas?

The 8.1 HCL was probably correct when it was written. If you look at the man page it actually only supports AR5XXX chipsets.The fact that it has attached to the ath driver (you have an ath0 device) shows that it is at least partly supported. Though reading this thread shows a similar level of support in 2.0.

The 5MHz antenna would make it practically useless at 2.4MHz but I would still expect to be able to 'see' it if you're very close, antennas are not perfect.